Glass fiber is an inorganic fiber material. Composite material with excellent performance can be obtained by reinforcing resin with glass fiber. As a reinforcing base material for advanced composite material, high-performance glass fibers were initially applied in defense and military fields, for example, the aerospace industry and weapons. With the advances in technology and the development of economy, high-performance glass fiber has been widely applied in fields of ordinary industry and civil affairs, for example, wind turbine blades, high-pressure containers, marine pipelines and automobile production.
The dominant component of the earliest high-performance glass is MgO—Al2O3—SiO2. The typical example is S-2 glass developed by Owens Corning company in U.S.A., which has a modulus of 89-90 GPa. However, the production of S-2 glass is difficult. The glass fiber forming temperature is as high as 1571° C., and the liquidus temperature is as high as 1470° C. It is difficult to realize large-scale tank furnace production. Therefore, the OC company gave up the production of S-2 glass fiber and assigned this patent right to AGY company in U.S.A.
Later, OC company further developed HiPer-tex glass having a modulus of 87-89 GPa. This is a tradeoff to reduce the production difficulty at the cost of certain glass performance. However, since this design only involves improvement to the S-2 glass, both forming temperature and the liquidus temperature of the glass fiber are still high and the production is still difficult. It is still difficult to realize large-scale tank furnace production. Therefore, OC company gave up the production of HiPer-tex glass fiber and assigned this patent right to 3B company in Europe.
Saint-Gobain company in France developed R glass containing MgO—CaO—Al2O3—SiO2 as the dominant component, having a modulus of 86-89 GPa. The conventional R glass has a high total content of Si and Al, there is no effective solution available to improve the crystallization performance of glass, and the ratio of Si to Mg is irrational. Consequently, the glass forming is difficult and the risk of crystallization is high. Meanwhile, the surface tension of the molten glass is high and it is very difficult for clarification. The glass fiber forming temperature reaches 1410° C. and the liquidus temperature reaches 1350° C. All of these lead to difficulty in the efficient drawing of glass fiber. It is still difficult to realize large-scale tank furnace production.
In China, Nanjing Fiberglass Research & Design Institute developed HS2 glass having a modulus of 84-87 GPa and containing SiO2, Al2O3 and MgO as the dominant components as well as Li2O, B2O3, CeO2 and Fe2O3. The forming temperature is only 1245° C. and the liquidus temperature is 1320° C., which are much lower than those for S glass. However, the forming temperature is lower than the liquidus temperature. The difference in temperature is denoted by ΔT, the value of which is negative. This is quite disadvantageous for the efficient drawing of glass fiber. It is necessary to increase the forming temperature and use special bushing tips to avoid the devitrification of glass during the drawing process. This leads to the difficulty in temperature control. It is still difficult to realize large-scale tank furnace production.
In conclusion, it has been found that at present various kinds of high-performance glass fiber generally have difficulties in tank furnace production, specifically manifested in high liquidus temperature, high crystallization rate, high forming temperature, high surface tension, high difficulty in clarification, and low or even negative value of ΔT. Because of this, in most companies, the production difficulty is reduced at the cost of certain glass performance. As a result, the performance of such high-performance glass fiber cannot be improved as the scale of production increases.